1. Field of the Invention
This invention relates to the sealing of inspection apertures and in particular to the sealing of inspection apertures in the casing of a gas turbine engine.
2. Description of Related Art
It is common practice to provide apertures in the casing of a gas turbine engine to facilitate the inspection of engine components such as those of the engine compressor, combustion equipment and turbine which are located within the casing. Typically those engine components are inspected using a device known as a boroscope. This is an elongate, usually flexible, device which is passed through the inspection aperture. It contains a light guide which permits viewing of otherwise inaccessible engine components.
Obviously when the engine has been inspected, the apertures must be sealed in order to prevent the leakage of high pressure gases which are present within those engine components during engine operation. Commonly the apertures are sealed by the positioning of a plug within the aperture.
While such sealing devices are usually effective in preventing the leakage of engine gases, it is possible for them to be improperly fitted or even not fitted at all after an inspection has been carried out. If this occurs, gas leakage will occur during engine operation. Such leakage is highly undesirable in view of the damage it can cause as well as result in a serious fall in engine efficiency and perhaps the activation of fire warning detectors.